Here are some keys to a great billboard site.
An unobstructed view to the freeway
The outside of a curve.
A long approach
A great right hand read that you know shows up in the center of your windshield.
A city that is willing to do business
A property that has a lot of land to work with
A property owner and a tenant on the property that understand that we’re going to be on the property for five days or longer when you are building out the structure
A property owner willing to provide the room that we need to service the sign once the billboard is built.
A property owner who allows you to trim the trees to keep the visibility to the road because that’s basically what we’re buying from the property owners the visibility to the freeway.
A good lease where both parties are satisfied with the terms.
Left hand reads sometime make sense.
There can be good left-hand reads especially on the outside curve. You’ve got nice visibility to the sign. A lot of times it looks like it’s dead ahead of you in the center of your windshield. The disadvantage of a left read and especially if it’s a low billboard you’re not just fighting the traffic heading in the same direction for visibility, but you’ve now got a problem with the opposing traffic blocking the view. In California you may have to look across 10 to 12 lanes of traffic to see a left read. If it’s less than 40 ft in the air you might not see it.
You can also check out this article on Billboard Insider.